//
//  NSDataCategory.m
//  ubixar-utils
//
//  Created by Demis Bellot on 17/04/2009.
//  Copyright 2009 __MyCompanyName__. All rights reserved.
//

#import "NSDataCategory.h"

#include <zlib.h>
@implementation NSData (NSDataExtension)

// Returns range [start, null byte), or (NSNotFound, 0).
- (NSRange) rangeOfNullTerminatedBytesFrom:(int)start
{
	const Byte *pdata = [self bytes];
	int len = [self length];
	if (start < len)
	{
		const Byte *end = memchr (pdata + start, 0x00, len - start);
		if (end != NULL) return NSMakeRange (start, end - (pdata + start));
	}
	return NSMakeRange (NSNotFound, 0);
}

+ (NSData *) dataWithBase32String:(NSString *)encoded
{
	/* First valid character that can be indexed in decode lookup table */
	static int charDigitsBase = '2';
	
	/* Lookup table used to decode() characters in encoded strings */
	static int charDigits[] =
	{	26,27,28,29,30,31,-1,-1,-1,-1,-1,-1,-1,-1 //   23456789:;<=>?
		,-1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,10,11,12,13,14 // @ABCDEFGHIJKLMNO
		,15,16,17,18,19,20,21,22,23,24,25,-1,-1,-1,-1,-1 // PQRSTUVWXYZ[\]^_
		,-1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,10,11,12,13,14 // `abcdefghijklmno
		,15,16,17,18,19,20,21,22,23,24,25                // pqrstuvwxyz
	};
	
	if (! [encoded canBeConvertedToEncoding:NSASCIIStringEncoding]) return nil;
	const char *chars = [encoded cString]; // avoids using characterAtIndex.
	int charsLen = [encoded cStringLength];
	
	// Note that the code below could detect non canonical Base32 length within the loop. However canonical Base32 length can be tested before entering the loop.
	// A canonical Base32 length modulo 8 cannot be:
	// 1 (aborts discarding 5 bits at STEP n=0 which produces no byte),
	// 3 (aborts discarding 7 bits at STEP n=2 which produces no byte),
	// 6 (aborts discarding 6 bits at STEP n=1 which produces no byte).
	switch (charsLen & 7) { // test the length of last subblock
		case 1: //  5 bits in subblock:  0 useful bits but 5 discarded
		case 3: // 15 bits in subblock:  8 useful bits but 7 discarded
		case 6: // 30 bits in subblock: 24 useful bits but 6 discarded
			return nil; // non-canonical length
	}
	int charDigitsLen = sizeof(charDigits);
	int bytesLen = (charsLen * 5) >> 3;
	Byte bytes[bytesLen];
	int bytesOffset = 0, charsOffset = 0;
	// Also the code below does test that other discarded bits
	// (1 to 4 bits at end) are effectively 0.
	while (charsLen > 0)
	{
		int digit, lastDigit;
		// STEP n = 0: Read the 1st Char in a 8-Chars subblock
		// Leave 5 bits, asserting there's another encoding Char
		if ((digit = (int)chars[charsOffset] - charDigitsBase) < 0 || digit >= charDigitsLen || (digit = charDigits[digit]) == -1)
			return nil; // invalid character
		lastDigit = digit << 3;
		// STEP n = 5: Read the 2nd Char in a 8-Chars subblock
		// Insert 3 bits, leave 2 bits, possibly trailing if no more Char
		if ((digit = (int)chars[charsOffset + 1] - charDigitsBase) < 0 || digit >= charDigitsLen || (digit = charDigits[digit]) == -1)
			return nil; // invalid character
		bytes[bytesOffset] = (Byte)((digit >> 2) | lastDigit);
		lastDigit = (digit & 3) << 6;
		if (charsLen == 2) {
			if (lastDigit != 0) return nil; // non-canonical end
			break; // discard the 2 trailing null bits
		}
		// STEP n = 2: Read the 3rd Char in a 8-Chars subblock
		// Leave 7 bits, asserting there's another encoding Char
		if ((digit = (int)chars[charsOffset + 2] - charDigitsBase) < 0 || digit >= charDigitsLen || (digit = charDigits[digit]) == -1)
			return nil; // invalid character
		lastDigit |= (Byte)(digit << 1);
		// STEP n = 7: Read the 4th Char in a 8-chars Subblock
		// Insert 1 bit, leave 4 bits, possibly trailing if no more Char
		if ((digit = (int)chars[charsOffset + 3] - charDigitsBase) < 0 || digit >= charDigitsLen || (digit = charDigits[digit]) == -1)
			return nil; // invalid character
		bytes[bytesOffset + 1] = (Byte)((digit >> 4) | lastDigit);
		lastDigit = (Byte)((digit & 15) << 4);
		if (charsLen == 4) {
			if (lastDigit != 0) return nil; // non-canonical end
			break; // discard the 4 trailing null bits
		}
		// STEP n = 4: Read the 5th Char in a 8-Chars subblock
		// Insert 4 bits, leave 1 bit, possibly trailing if no more Char
		if ((digit = (int)chars[charsOffset + 4] - charDigitsBase) < 0 || digit >= charDigitsLen || (digit = charDigits[digit]) == -1)
			return nil; // invalid character
		bytes[bytesOffset + 2] = (Byte)((digit >> 1) | lastDigit);
		lastDigit = (Byte)((digit & 1) << 7);
		if (charsLen == 5) {
			if (lastDigit != 0) return nil; // non-canonical end
			break; // discard the 1 trailing null bit
		}
		// STEP n = 1: Read the 6th Char in a 8-Chars subblock
		// Leave 6 bits, asserting there's another encoding Char
		if ((digit = (int)chars[charsOffset + 5] - charDigitsBase) < 0 || digit >= charDigitsLen || (digit = charDigits[digit]) == -1)
			return nil; // invalid character
		lastDigit |= (Byte)(digit << 2);
		// STEP n = 6: Read the 7th Char in a 8-Chars subblock
		// Insert 2 bits, leave 3 bits, possibly trailing if no more Char
		if ((digit = (int)chars[charsOffset + 6] - charDigitsBase) < 0 || digit >= charDigitsLen || (digit = charDigits[digit]) == -1)
			return nil; // invalid character
		bytes[bytesOffset + 3] = (Byte)((digit >> 3) | lastDigit);
		lastDigit = (Byte)((digit & 7) << 5);
		if (charsLen == 7) {
			if (lastDigit != 0) return nil; // non-canonical end
			break; // discard the 3 trailing null bits
		}
		// STEP n = 3: Read the 8th Char in a 8-Chars subblock
		// Insert 5 bits, leave 0 bit, next encoding Char may not exist
		if ((digit = (int)chars[charsOffset + 7] - charDigitsBase) < 0 || digit >= charDigitsLen || (digit = charDigits[digit]) == -1)
			return nil; // invalid character
		bytes[bytesOffset + 4] = (Byte)(digit | lastDigit);
		//// This point is always reached for chars.length multiple of 8
		charsOffset += 8;
		bytesOffset += 5;
		charsLen -= 8;
	}
	// On loop exit, discard the n trailing null bits
	return [NSData dataWithBytes:bytes length:sizeof(bytes)];
}

- (NSString *) base32String
{
	/* Lookup table used to canonically encode() groups of data bits */
	static char canonicalChars[] =
	{	'A','B','C','D','E','F','G','H','I','J','K','L','M' // 00..12
		,'N','O','P','Q','R','S','T','U','V','W','X','Y','Z' // 13..25
		,'2','3','4','5','6','7'                             // 26..31
	};
	const Byte *bytes = [self bytes];
	int bytesOffset = 0, bytesLen = [self length];
	int charsOffset = 0, charsLen = ((bytesLen << 3) + 4) / 5;
	char chars[charsLen];
	while (bytesLen != 0) {
		int digit, lastDigit;
		// INVARIANTS FOR EACH STEP n in [0..5[; digit in [0..31[;
		// The remaining n bits are already aligned on top positions
		// of the 5 least bits of digit, the other bits are 0.
		////// STEP n = 0: insert new 5 bits, leave 3 bits
		digit = bytes[bytesOffset] & 255;
		chars[charsOffset] = canonicalChars[digit >> 3];
		lastDigit = (digit & 7) << 2;
		if (bytesLen == 1) { // put the last 3 bits
			chars[charsOffset + 1] = canonicalChars[lastDigit];
			break;
		}
		////// STEP n = 3: insert 2 new bits, then 5 bits, leave 1 bit
		digit = bytes[bytesOffset + 1] & 255;
		chars[charsOffset + 1] = canonicalChars[(digit >> 6) | lastDigit];
		chars[charsOffset + 2] = canonicalChars[(digit >> 1) & 31];
		lastDigit = (digit & 1) << 4;
		if (bytesLen == 2) { // put the last 1 bit
			chars[charsOffset + 3] = canonicalChars[lastDigit];
			break;
		}
		////// STEP n = 1: insert 4 new bits, leave 4 bit
		digit = bytes[bytesOffset + 2] & 255;
		chars[charsOffset + 3] = canonicalChars[(digit >> 4) | lastDigit];
		lastDigit = (digit & 15) << 1;
		if (bytesLen == 3) { // put the last 1 bits
			chars[charsOffset + 4] = canonicalChars[lastDigit];
			break;
		}
		////// STEP n = 4: insert 1 new bit, then 5 bits, leave 2 bits
		digit = bytes[bytesOffset + 3] & 255;
		chars[charsOffset + 4] = canonicalChars[(digit >> 7) | lastDigit];
		chars[charsOffset + 5] = canonicalChars[(digit >> 2) & 31];
		lastDigit = (digit & 3) << 3;
		if (bytesLen == 4) { // put the last 2 bits
			chars[charsOffset + 6] = canonicalChars[lastDigit];
			break;
		}
		////// STEP n = 2: insert 3 new bits, then 5 bits, leave 0 bit
		digit = bytes[bytesOffset + 4] & 255;
		chars[charsOffset + 6] = canonicalChars[(digit >> 5) | lastDigit];
		chars[charsOffset + 7] = canonicalChars[digit & 31];
		//// This point is always reached for bytes.length multiple of 5
		bytesOffset += 5;
		charsOffset += 8;
		bytesLen -= 5;
	}
	return [NSString stringWithCString:chars length:sizeof(chars)];
}

#define FinishBlock(X)  (*code_ptr = (X),   code_ptr = dst++,   code = 0x01)

- (NSData *) encodeCOBS
{
	if ([self length] == 0) return self;
	
	NSMutableData *encoded = [NSMutableData dataWithLength:([self length] + [self length] / 254 + 1)];
	unsigned char *dst = [encoded mutableBytes];
	const unsigned char *ptr = [self bytes];
	unsigned long length = [self length];
	const unsigned char *end = ptr + length;
	unsigned char *code_ptr = dst++;
	unsigned char code = 0x01;
	while (ptr < end)
	{
		if (*ptr == 0) FinishBlock(code);
		else
		{
			*dst++ = *ptr;
			code++;
			if (code == 0xFF) FinishBlock(code);
		}
		ptr++;
	}
	FinishBlock(code);
	
	[encoded setLength:((Byte *)dst - (Byte *)[encoded mutableBytes])];
	return [NSData dataWithData:encoded];
}

- (NSData *) decodeCOBS
{
	if ([self length] == 0) return self;
	
	const Byte *ptr = [self bytes];
	unsigned length = [self length];
	NSMutableData *decoded = [NSMutableData dataWithLength:length];
	Byte *dst = [decoded mutableBytes];
	Byte *basedst = dst;
	
	const unsigned char *end = ptr + length;
	while (ptr < end)
	{
		int i, code = *ptr++;
		for (i=1; i<code; i++) *dst++ = *ptr++;
		if (code < 0xFF) *dst++ = 0;
	}
	
	[decoded setLength:(dst - basedst)];
	return [NSData dataWithData:decoded];
}

// --------------------------------CRC32-------------------------------
static const unsigned long crc32table[] =
{
0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, 0x706af48f, 0xe963a535, 0x9e6495a3,
0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988, 0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91,
0x1db71064, 0x6ab020f2, 0xf3b97148, 0x84be41de, 0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7,
0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9, 0xfa0f3d63, 0x8d080df5,
0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172, 0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b,
0x35b5a8fa, 0x42b2986c, 0xdbbbc9d6, 0xacbcf940, 0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59,
0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423, 0xcfba9599, 0xb8bda50f,
0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924, 0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d,
0x76dc4190, 0x01db7106, 0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433,
0x7807c9a2, 0x0f00f934, 0x9609a88e, 0xe10e9818, 0x7f6a0dbb, 0x086d3d2d, 0x91646c97, 0xe6635c01,
0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e, 0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457,
0x65b0d9c6, 0x12b7e950, 0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65,
0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2, 0x4adfa541, 0x3dd895d7, 0xa4d1c46d, 0xd3d6f4fb,
0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0, 0x44042d73, 0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9,
0x5005713c, 0x270241aa, 0xbe0b1010, 0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17, 0x2eb40d81, 0xb7bd5c3b, 0xc0ba6cad,
0xedb88320, 0x9abfb3b6, 0x03b6e20c, 0x74b1d29a, 0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683,
0xe3630b12, 0x94643b84, 0x0d6d6a3e, 0x7a6a5aa8, 0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1,
0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb, 0x196c3671, 0x6e6b06e7,
0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc, 0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5,
0xd6d6a3e8, 0xa1d1937e, 0x38d8c2c4, 0x4fdff252, 0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b,
0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55, 0x316e8eef, 0x4669be79,
0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236, 0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f,
0xc5ba3bbe, 0xb2bd0b28, 0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d,
0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x026d930a, 0x9c0906a9, 0xeb0e363f, 0x72076785, 0x05005713,
0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38, 0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21,
0x86d3d2d4, 0xf1d4e242, 0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777,
0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c, 0x8f659eff, 0xf862ae69, 0x616bffd3, 0x166ccf45,
0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2, 0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db,
0xaed16a4a, 0xd9d65adc, 0x40df0b66, 0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605, 0xcdd70693, 0x54de5729, 0x23d967bf,
0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94, 0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d
};

- (unsigned int)crc32
{
	unsigned int	crcval;
	unsigned int	x, y;
	const void		*bytes;
	unsigned int    max;
	
	bytes = [self bytes];
	max = [self length];
	crcval = 0xffffffff;
	for (x = 0, y = max; x < y; x++) {
		crcval = ((crcval >> 8) & 0x00ffffff) ^ crc32table[(crcval ^ (*((unsigned char *)bytes + x))) & 0xff];
	}
	
	return crcval ^ 0xffffffff;
}


@end